Laser level assembly

ABSTRACT

Disclosed is a laser surveying apparatus including a body, a platform pivotally supported by the body about a first axis, a drive pivotally supported by the platform about a second axis transverse to the first axis, a head rotatably supported by the drive to rotate about a third axis transverse to the second axis, and a semiconductor laser supported by the head to project laser radiation transverse the third axis. Electrical power to the laser is supplied via rotatable connections thereby allowing the weight of a power source to be omitted from the rotating head. Selective adjustments of the head allow the laser to rotate in a horizontal plane, a vertical plane or an inclined plane. Selective adjustment of the platform permits the laser to irradiate in a vertical plane at differing horizontal angles so facilitating marking out of buildings, fences etc. In one form the laser may be used as a plumb line and shine through the platform and body down upon a style thereby facilitating accurate location of the apparatus. The laser and drive in one form are remotely controlled to effect rotation, on/off of the laser, and dither action of the laser.

FIELD OF THE INVENTION

The invention disclosed herein relates to a laser level assembly. Thelaser level assembly is an apparatus that provides a laser beam whichcan be used for applications including but not limited to surveying andconstruction levelling and marking out.

BACKGROUND OF THE INVENTION

The use of a rotating laser beam to define a plane is well known. Thesedevices have typically incorporated a semiconductor laser fixed within ahousing projecting its laser light beam into a spinning prism whicheffects translation of a typically vertically projected beam into arotating horizontal beam. Attachments have been available which in likemanner effect a rotating vertical laser beam, however these require thedismantling of a set up device to permit fitting. Therefore the devicemust be relocated and reset when changing from a horizontal rotatinglaser beam to a vertical rotating laser beam.

In such arrangements the laser beam is projected along the axis aboutwhich a platform supporting a prism rotates. An electric motor is usedto drive the platform typically through a belt or gear cog arrangement.Thus, the known devices rotate fully about an axis defining a fullplane. This means that there can be a significant delay at a remotesensing location for the beam to rotate between each transversing of thelocation. The speed of rotation may be variable but this can lead to afurther problem. The effective angular velocity can be very high withthe effect that the laser radiation flux experienced by a sensor may betoo low to be reliably sensed. Thus increasing the speed of rotation canlead to unreliable sensing of the laser beam so requiring a slower speedof rotation, and slowing the speed of rotation increases the timebetween each transversing by the beam of the sensor. Electronic designof the sensor may accommodate some of these problems.

Further problems are exhibited by the known systems. The use of qualityoptical elements such as a prism leads to an expensive device. Further,the mechanical supporting structure also typically needs to be to a veryhigh tolerance with the result again that the device is expensive.

To overcome some of these problems a number of devices have beenproposed.

U.S. Pat. No. 5,287,365 to Nielsen et al describes a laser apparatuswhere a semiconductor laser is mounted onto a platform which is rotatedby an electric motor. The platform has a central shaft which is drivenby an electric motor through a belt drive. Electrical power istransferred to the shaft and thus to the laser through slip rings.Control of the electrical motor is limited to on/off and speed control.

As disclosed the apparatus provides essentially a horizontal plane inwhich the laser beam rotates.

In U.S. Pat. No. 4,973,158 to Marsh an instrument is disclosed which isintended to be fitted to a surveyor's transit and telescope. It isdisclosed as rotating in a vertical plane aligned with the plane of viewof a telescope. There is no disclosure of being able to change the planeof laser beam rotation in a convenient and simple manner. Rather theinstrument is limited to improvements related to a transit level ratherthan a more general instrument.

The disclosed device utilises a rotatable shaft which has a platform ateach end. A semiconductor laser is mounted on one platform with driveand control circuitry mounted on the other platform. To power the laser,electrical power is supplied to the platforms through electrical brushesto the shaft. The shaft and the platforms are rotated by an electricmotor through gear cogs.

In U.S. Pat. No. 5,400,514 to Imbrie et al an apparatus is disclosedwhere a laser pointer is centrally supported on a shaft. The shaft isbelt driven to rotate by an electric motor within a rectilinear body.The electrical and electronic circuitry for the electric motor and thelaser pointer are completely separate. The laser pointer includes drivecircuitry and battery for electrical power supply independent of therest of the apparatus. Accordingly, the electrical motor must rotate thesemiconductor laser and the necessary circuitry.

The body of the apparatus disclosed does include means to set up theapparatus so that the plane within which the laser radiation projects iseither vertical or horizontal. For this purpose three orthogonallymounted spirit bubble levels are provided with two sets of adjustablefeet projecting from adjacent sides. To change the plane within whichthe laser beam rotates the apparatus must be set up afresh.

It is a proposed object of this invention to provide an apparatus toobviate or minimise at least one of the aforementioned problems, or atleast provide the public with a useful choice

SUMMARY OF THE INVENTION

The invention may be said to reside, not necessarily in the broadest oronly form, in laser level apparatus including body means, platform meanssupported by the body means and selectively pivotable about a firstaxis, drive means supported by the platform means and selectivelypivotable about a second axis transverse to the first axis, head meansrotatably supported by the drive means and adapted to be selectivelyrotated by the drive means about a third axis transverse to the secondaxis, laser means supported by the head means to selectively projectlaser radiation from the head means transverse the third axis, lasermeans includes a semiconductor laser adapted to produce the laserradiation, and the apparatus includes a first rotatable electricalconnection means and a second rotatable electrical connection meansthrough which electrical power is supplied to the semiconductor laser.

In another preferred form, the drive means includes a motor with arotatable shaft driven thereby which is coaxial with the second axis andthe head means is supported by the shaft.

In one preferred form, wherein the shaft has two partly coaxialelectrically conductive parts insulated one from the other, and thefirst rotatable electrical connection means and the second rotatableelectrical connection means each includes a respective one of the parts.According to a preferred form, the first rotatable electrical connectionmeans and the second electrical connection means respectively includeselectrical brush arrangements. It will be appreciated that otherarrangements known to the art similar in effect to the electrical brusharrangement can be used as desired.

The separation of the laser means and the electrical power source meansthe weight of the laser means can be reduced so easing the loadexperienced by the drive means during rotating the laser head. In onepreferred form, the laser means may be rotated and varying andrelatively high speeds and dithered within an arc. For such action it isdesirable for the rotating laser means to have a relatively low inertia.

It will be appreciated that the ability to rotate the various parts ofthe apparatus with respect to other parts permits flexibility and easeof use.

In a preferred form, the laser radiation projected by the laser means issubstantially perpendicular to the third axis, the third axis issubstantially perpendicular to the second axis, the second axis issubstantially perpendicular to the first axis, and the drive means maybe selectively rotated to a first configuration where the third axis issubstantially parallel or coaxial with the first axis and to a secondconfiguration where the third axis is substantially perpendicular to thefirst axis.

In a further preferred form, the body means has levelling means toenable adjustment of the support of the platform means such that thefirst axis is within a vertical plane, and thereby when the apparatus isin the first configuration the laser radiation projected by the lasermeans is substantially within a horizontal plane and when the apparatusis in the second configuration the laser radiation projected by thelaser means is substantially within a vertical plane. By levelling thebody means so that the first axis is vertical the laser beam can berotated in a horizontal or vertical plane. In the case of a verticalplane the platform means can be rotated about the first axis sopermitting the vertical plane and a subsequent vertical plane to be at aknown horizontal angle one with respect to the other. This can be used,for example, to set out two adjacent sides of a building.

According to one preferred form, the drive means may be selectivelyrotated and secured in a configuration between the first and secondconfigurations. This permits the plane within which the laser beamrotates to be a sloping plane. This can be used, for example, toindicate a slope for earth moving machinery to work to as may berequired for drainage control of a land site.

According to a preferred form, the apparatus is one including levellingmeans acting between the body means and the platform means. In apreferred form, the levelling means includes two spirit bubbles settransverse to each other and within or upon the platform means forindication of levelness of the platform means, and foot screws spacedabout the platform means and acting against the body means with which toadjust the relative position of the platform means with respect to thebody means and thereby with the spirit bubbles permit the levelling ofthe platform means. In an alternative preferred form, the levellingmeans includes two spirit bubbles set transverse to each other andwithin or upon the platform means for indication of levelness of theplatform means, and the platform means includes a shaft projectingsubstantially perpendicular to a platform plate and substantiallyparallel to the first axis into the body means through a first hole andat substantially a distal end of the shaft, two spring means act to biasthe shaft against the action of two radially spaced transverse actingscrews with which the platform means may be levelled by tilting theshaft relative to the body means. In a further preferred alternativeform, the levelling means includes semi-automated or automated means toeffect levelling of the platform means.

In another preferred form, the apparatus is one including a stand forsupporting the body means in an elevated position above a floor orground surface. In a preferred form the body means is adapted to restupon an suitable relatively flat surface. For example a table top orother surface which is reasonably flat and level to support theapparatus and permit levelling of the platform means relative to thebody means.

In a preferred form, either the platform means includes a graduatedcircular scale and the body means includes an indicator mark or viceversa, therewith the rotation of the platform means about the first axiscan be determined. By use of the scale an indication of rotation of theplatform means with respect to the body means can be provided. In apreferred form, the graduated circular scale is selectively rotatableand securable thereby permitting the scale to be set to the indicatormark and the platform means rotated a desired quantity of rotationindicated by the scale. In this manner a vertical plane of laser beamrotation may be set a specific angle relative to a previous verticalplane of laser beam rotation. In a preferred form, the platform means orthe body means as the case may be includes a ring upon which theindicator mark is, and the ring is selectively rotatable and securablethereby permitting the indicator mark to be rotated to a point closestto the graduated circular scale. Should the body means and the platformmeans be angled one to the other then the plane of the graduated scaleand the ring will also be angled. Accordingly there will be a side wherethe ring and scale are closest and a side opposite where they arefurthest. Thus to improve accuracy and ease of operation it is desirableto adjust the indicator mark to be as near as possible to the scale.

According to a preferred form, either the platform means includes agraduated scale and the drive means includes an inclination mark or viceversa, therewith the rotation of the drive means about the second axiscan be determined and set thereto.

In another preferred form, the drive means includes an electric motorand control means to control the rotational position thereof. In apreferred form, the drive means includes an electric stepper motor andcontrol means to control the rotational position thereof and the activestate of the laser means. In preference, the control means is containedwithin the platform means and connected to the stepper motor and lasermeans via electrical wiring. Preferably, the control means permitscontrol of the stepper motor such that it may be rotated to a desiredrotational position, continually rotating about the third axis, oroscillating between two rotational positions. It will be appreciatedthat other forms of motors may be used as desired.

In a preferred form, the laser head includes means to collimate thelaser with respect to the third axis. This permits adjustment so thatthe third axis is perpendicular to the plane within which the laseremits a rotating beam of radiation. In a preferred form, the laser headincludes support means for supporting the laser within the laser head,the support means including a resilient first bearing means adapted toprovide a firm hold of the laser, and a second bearing means including aresilient bearing surface against which and along a collimator axissubstantially parallel to the third axis an adjustable means presses thelaser. In this manner, the first bearing permits slight rotation of thelaser in response to adjustment of the adjustable means which can beused to collimate the laser with respect to the third axis. A lockingmeans to secure the laser in place after collimation can be incorporatedas desired.

According to a preferred form, the apparatus is one including a remotecontrol unit adapted to transmit control setting signals to a receiverwithin the control means thereby to effect control of the stepper motorand the laser means.

In a preferred form, there is provided an apparatus, substantially asherein described, and a detector staff with an array of detectors eachfor detection of the laser radiation. In preference, the array ofdetectors includes two sets of the detectors each set being alignedalone intersecting first and a second line such that the detectors forma cross. Other intersecting forms can be used as desired. In a preferredform, the laser radiation is emitted in a plane and the detector arrayis moved so that it is aligned with either the first or the second lineand the control means is commanded to effect reduced dithering of thelaser radiation within the plane until the laser radiation is emitted ina single direction, whereafter the detector array can be centered withrespect to the laser radiation.

Without limiting the invention disclosed herein, one known systemincluding a laser level instrument and a remote control is disclosed inPCT Patent Application WO 96/01978.

In one preferred form, the platform means and body means have aperturemeans such that the first axis is unobstructed and that the laser meansmay project laser radiation through the platform means and body means.Further, according to one form the drive means is supported by theplatform means so as to be rotatable through 180° relative to theplatform means. By this means the laser may be orientated to shinethrough the platform and body means and may be used as a plumb line.Also setting the apparatus above a style, levelling the apparatus and bythen using the plumb line feature the apparatus may be accuratelylocated relative to the style. Once so set up rotation of the platformmeans with respect to the body means does not change the first axisbeing within the plane of the laser radiation. This may facilitatemarking out of lines such as for walls and fences.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist in the understanding of the invention preferred embodimentswill now be described with reference to the accompanying drawings:

FIG. 1 is a sketch of the apparatus;

FIG. 2 is a sketch of the apparatus similar to FIG. 1 showing adifferent orientation of the drive means;

FIG. 3 is a cross sectional view of drive means illustrating theelectrical arrangement and the mounting arrangement;

FIG. 4(a) is a cross sectional view of the body means illustrating thelevelling means;

FIG. 4(b): is a cross sectional view along AA;

FIG. 5(a) is a sketch of a manner in which the apparatus can be usedwith a remote control device;

FIG. 5(b) is a sketch of the detector staff;

FIG. 6 is a schematic sketch of the electronic circuitry controlling themotor;

FIG. 7 is a schematic sketch of a preferred means for enablingcollimation of the laser;

FIG. 8 is a sketch of a second embodiment with the laser head in oneconfiguration;

FIG. 9 is a sketch of the second embodiment with the laser head inanother configuration;

FIG. 10 is a sketch of the second embodiment with the laser head in yetanother configuration; and,

FIG. 11 is a sketch of a cross section view of the second embodiment;

FIG. 12 is a sketch of the third embodiment with the laser head in yetanother configuration;

FIG. 13 is a spread of the spot beam of the laser such as a line;

FIG. 14 is a spread of the spot beam of the laser such as twointersecting orthogonal lines.

DETAILED DESCRIPTION OF THE INVENTION

It will be appreciated that the accompanying drawings are not toengineering standard or are intended to be engineering constructiondrawings. Rather the drawings are schematic and somewhat symbolic. Theintention is to illustrate the invention and the concepts associatedtherewith such that a skilled addressee can understand the invention andapply it as they desire. Accordingly, perspective and illustratedfeatures may be distorted or omitted in the interest of facilitatingunderstanding and convenience of drawing. Throughout the drawings thesame numerical reference number will be used to refer to the samefeature.

In broad terms the apparatus (1) includes body means (2). Supported bythe body means and selectively pivotable about a first axis, asindicated by (3), are platform means (4). Supported by the platformmeans and selectively pivotable about a second axis, as indicated by(5), transverse to the first axis are drive means (6). Rotatablysupported by the drive means and adapted to be selectively rotated bythe drive means about a third axis, as indicated by (7), transverse tothe second axis are head means (8). Supported by the head means arelaser means (9) adapted to selectively project laser radiation from thehead means transverse the third axis.

The construction of the apparatus is such that the laser radiationprojected by the laser means is substantially perpendicular to the thirdaxis, the third axis is substantially perpendicular to the second axis,the second axis is substantially perpendicular to the first axis, andthe drive means may be selectively rotated to a first configurationwhere the third axis is substantially parallel or coaxial with the firstaxis and to a second configuration where the third axis is substantiallyperpendicular to the first axis. Comparison of FIGS. 1 and 2 illustratesthe first and second configuration of the drive means and from this itwill be seen that the apparatus permits easy conversion and set-up froma vertical plane to a horizontal plane in which the laser beam rotates.It will be appreciated that the first and second configurations whilstin this embodiment are extremes in other embodiments the drive means maybe rotatable with respect to the platform means through a greater angle.

The body means may be mounted onto a tripod stand having legs (10, 11and 12) and platform (13). The body means can be secured to the platform(13) with a suitable bolt co-acting with threaded hole (14). Thispermits the apparatus to be set up in an elevated and relatively stableposition should this desired. The tripod and its use would be well knownto a skilled addressee.

The body means is adapted to be supported by a suitable reasonably flatand sized surface. The body means has an annular rim (60) about thebottom of the body means with which the apparatus can be supported onsuch a suitable surface. Examples of suitable surfaces can include atable top and a fence post top. It will be appreciated that theapparatus should be supported in a stable fashion and the platform meanslevelled. If the surfaces is not reasonably flat then the levellingadjustment may be beyond that provided in the apparatus.

The platform means has two spirit bubbles (15 and 16) set within it andwithin a general disc like supporting plane (17) of the platform means.These spirit bubbles are set transverse one to the other so that thebubbles within each can be used to indicate levelness of the supportingplane. The supporting plane is the topmost portion of a coaxial platformplate (18) which forms the lower part of the platform means (4).

Centrally projecting from the platform plate and perpendicular theretois a hollow shaft (19). The hollow shaft enters into the top of the bodymeans through a suitable top aperture (20) and through a bottom aperture(21) within an internal web (22) of the body means. Supporting thehollow shaft is a top spherical bearing (23). This permits the shaft toa limited extent to be intentionally misaligned, tilted, with the axisof the top aperture. The bottom aperture is somewhat larger than thehollow shaft to permit selective misalignment of the hollow shaft withrespect to a lower spherical bearing (24) held within a support means.

The support means includes two transverse compression springs (25 and26) each acting against the influence of two transverse bolts (27 and28). This arrangement biases the shaft towards the bolts and byadjustment of each bolt the shaft can be tilted with respect to the bodymeans.

This permits the levelling of the platform means by tilting the shaftwithin a limited range. Once the apparatus is roughly levelled byadjusting the tripod or placement upon a suitable surface furtherlevelling of the platform means (4) is effected by the selective tiltingof the shaft.

Also within the body means are electrical batteries (29 and 30). Thesesupply electrical power to the laser means and other circuitry andcomponents. To transfer power from the batteries connectors to thebatteries connect to terminals. These pass through the internal web (22)and are connected to electrical cable, such as a twin core flex (31).The electrical cable is passed through the shaft (19) to a controlcircuit board (32) within the platform means.

Rotation of the platform means can be limited by a suitable stop actingbetween it and the body means. This allows near 360° rotation ofplatform means, typically greater than 270°. with respect to the bodymeans. Further, there is provided platform locking means, a bolt actingbetween the body means and the platform means, which can secure theplatform means relative to the body means. This arrangement prevents theelectrical cable becoming excessively twisted. The flexibility in theelectrical cable permits a flexible electrical connection to be madebetween the batteries and the circuit board.

Projecting from the platform means are two spaced and essentiallycentrally positioned mounting arms (33 and 34). Between these arms isrotatably supported the drive means (6) on pivots (35 and 36) whichalign with the second axis. The pivots or at least one thereof includesdrive locking means, such as a not acting on a threaded shaft, withwhich the relative position of the platform means and the drive meanscan be secured. Also provided is an inclination marker (37) on the arm(33) and a graduated scale (38) fixed to the pivot (35) such thatrotation of the drive means effects rotation of the scale relative tothe inclination marker.

By use of the scale, inclination marker and the drive locking means itis possible to set the plane within which the laser beam rotates. Thisis accurate enough for some practical applications but in others, wherethe angle of inclination is critical, more precise means of settinginclination can be used. The apparatus, including the laser drive means,could be adjusted so that the laser beam passes through a number ofpoints determined using other methods and instruments.

In another form, the supporting plane can incorporate one or moregraduated scale spirit bubbles. These could be 4% inclination full scaleand are known to the art. There could be two which are transverse one tothe other and thereby the platform means may be adjusted to a desiredinclination. Accordingly, the plane of the laser beam is also adjustedto that inclination or to a plane relative thereto. In another form, asingle graduated scale spirit bubble is provided.

Within the drive means is mounted an electric stepper motor (39). Inthis embodiment a stepper motor is used but it will be appreciated thatother motors may be used as desired. For example, a D.C. chopper motorcould be used where the rotor of the motor includes a vane whichinterrupts a light beam of a photodiode and photo-transistor arrangementand upon interruption the polarity of the D.C. voltage to the motor isreversed thereby effecting a reversal in rotation direction.

To the metal motor shaft (40) of the stepper motor is fitted a furthermetal outer shaft (41) insulated from the motor shaft. By use ofelectrical brushes (42) positive potential electrical power is passed tothe motor shaft. Through a further set of electrical brushes (43)negative electrical power is passed to the outer shaft.

The outer shaft passes out of the drive means. Mounted to the outershaft is the head means (8) within which is mounted the laser means (9),a low power semiconductor laser. This device requires low voltage D.C.electrical power. This can be supplied through electrical cables (44,45, 46 and 47) and the electrical brushes from the control circuitboard. The control circuit board includes drive circuitry to control thelaser means and is powered from the batteries through cable (31) alreadydiscussed. The control circuit board also includes drive and controlcircuitry for the stepper motor and electrical connection from thecontrol circuit board to the stepper motor is through cables (48 and49); that is, as will be appreciated by a skilled addressee, fourcontrol and power lines for the stepper motor.

To facilitate changing vertical planes within which the laser beamrotates the platform means has an indicator or rotation marker (50) upona ring (61) coaxially rotatable about the platform means, a rotatablegraduated scale (51) and locking mechanism (52). Once the lockingmechanism, a bolt acting against the platform plate (18), is unlockedthe scale (51) is freely rotatable about the platform means but notaxially moveable. Likewise the ring and rotation marker are securableand rotatable to and about the platform means. Initially the rotationmarker is rotated until it is proximal to the smallest gap between thegraduated scale on the body and the ring on the platform means. It isthen secured in place.

To change from one vertical plane to another at a predetermined angle tothe first the scale is rotated and zeroed to the rotation marker. Thenthe scale is secured with the locking mechanism. Next the platform meansis rotated, with respect to the body means, by the desired angle asindicated by the scale and rotation marker thereby effecting thetranslation of the plane of rotation of the laser beam to a new desiredplane. The above is applicable, for examples, to marking out foundationsfor buildings and property boundary fences.

To protect the apparatus the drive means and upper portion of platformmeans are covered by a removable dome (53). In the figures it isillustrate as being transparent to permit easy checking of inclinationof the plane within which the laser beam rotates but this is a matter ofchoice. The dome has a slot (54) though which the outer shaft (41)projects thereby supporting the laser head (8) outside of the dome. Theslot permits variation of the inclination of the laser head and therotation thereof about the second axis.

Switches for control of the apparatus through their effect on thecontrol circuit board are mounted in the platform means to be accessibleexternally thereto. These are not shown but take a form known to theart. Wire cabling connects the switches to the control circuit board.

Further, the control circuit board and platform means also incorporatesa receiver means. This, with a remote control device capable oftransmitting signals adapted to be detected by the receiver means,permits remote control of the apparatus. Again, the details of this donot form part of the invention and take forms generally known to theart. In a preferred form the remote control use a low power radio linkto transmit commands to the receiver means.

The control circuit board contains a circuit, the details of which donot form part of the invention and take forms generally known to theart. The circuit includes a micro controller (62) and suitablecircuitry. See FIG. 6 but note that the details of the receiver meansare not illustrated but take prior known forms. The micro controllerruns software stored in an internal EPROM which permits a number offunctions to be achieved dependant upon a user's control of the switchesvia connections (63) or via a serial link (64) from the receiver. Themicro controller can effect operation and control of the laser means,the speed with which the laser is rotated by the stepper motor, and thedirection of rotation.

The micro controller generates control signals which motor controlintegrated circuit (65) uses to control driver integrated circuit (66).The micro controller generates a series of pulses on line (EN) with 400pulses equates to a full rotation of the stepper motor. The frequency ofthe pulses is between 200 Hz and 3000 Hz in 200 Hz steps. This providesa laser rotation speed of 30 rpm to 450 rpm.

The micro controller also generates a rotation direction signal on line(CW) to control the direction of rotation of the motor.

For correct operation of the stepper motor the maximum start up thepulse frequency is limited to 1600 Hz and the micro controller willdefault to this should the speed of the last rotation have required agreater frequency than this. Likewise the speed is controlled when thedirection of rotation is altered. For similar reasons the maximum ditherspeed is limited to a pulse frequency of 800 Hz.

The dither is controlled by the micro controller to occur about thedirection just prior to the micro controller receiving a request fordither mode. The minimum range is ±10 pulses with a maximum range of±100 which corresponds to 18° to 180° dither range. Whilst in the dithermode the frequency of rotation can be increased up to the maximum aboveand the width of the dither can be varied. Also the centre line of thedither can be rotated clockwise or counter clockwise as desired.

It will be appreciated that the minimum and maximum values have beenselected for the particular embodiment and are a matter of choice inview of the embodiment.

Further the rotational position of the laser beam within the plane canbe set so that the laser projects along a certain line by control of thestepper motor. Also the stepper motor can be controlled to ditherbetween two selected extremes so that the laser beam effectivelyoscillates between two extremes such a ±10° from a central line underthe control of a user.

As is known to the art, in high ambient light levels the laser beam canbe difficult to see. It is known to use a device including a detectoradapted to detect the laser beam and provide either or both an audio orvisual indication when the laser beam is detected. The apparatusdisclosed herein with a remote control permits easy and simple controlof the laser from a distance. For this a detector staff is used whichhas nine laser beam detectors aligned in two substantially orthogonalintersecting sets as illustrated in FIG. 5(b).

The user (55) can set up the apparatus to provide a horizontal beam butdithering about a desired direction and between a limited range coveringthe general vicinity where a position mark is required. Then the usercan walk away to the general vicinity where a position mark is required.By adjusting the height of the detector array (56) along a staff (57) sothat the horizontal detectors are transversed by the laser beam the usercan determine the desired level. Then using the remote control (58) theuser can command the apparatus to reduce the dither move the staff sothat the detector array detects the laser beam. By repeating the processof reducing the dither and following the laser beam until there is nodither but a spot then a desired line and level can be located andmarked out. It will be appreciated that when the central detector (59)is detecting the laser beam projected along a desired line then thelevel and direction of the position is indicated.

The laser (9) is substantially cylindrical in shape. It is mounted tothe laser head (8) through an elastomer bearing at each end. In FIG. 7this is illustrated in schematic form with other features, such aselectrical wiring omitted for clarity. FIG. 7(a) is a plan view. FIG.7(b) is a side view, FIG. 7(c) is an end view looking into the laser.FIG. 7(d) is a plan view with the lid removed, and FIG. 7(e) is a crosssectional view along BB′.

The laser head is box like mounted on shaft (41) and has a lid (72)secured by screws (73, 74, 75 and 76). These screws screw into threadedholes (77, 78, 79 and 80).

At one end of the laser the bearing takes the form of an “O” ring (67)supported and retained between wall members (81, 82, 83, 84) of thelaser head. The bearing at the other end includes a “U” shaped elastomerblock (68) supported and retained by member (85) and portion (86) of thelaser head. In this manner the bearings are held within channels. The“O” ring is compressed by the lid to firmly hold the laser.

The laser is held between the legs of the “U” shape and is biasedupwards by the flat portion of the “U” shape (69). A threaded screw (70)co-acting with a threaded hole in the lid presses the laser against theflat portion of the “U” shape and a second screw (71), co-acting with athreaded hole within portion (86), transverse to the first is used tolock the laser in place. By loosening the locking screw and adjustingthe first the laser can be tilted relative to the laser head. In thismanner the laser can be collimated so as to rotate within a planeperpendicular to the third axis. Once collimation is achieved thelocking screw is used to secure the laser in place.

The second embodiment illustrated in FIGS. 8, 9, 10 and 11 is amodification of the first embodiment. In the interest of brevity partspreviously discussed with respect to the first embodiment will not bediscussed again in respect of the second embodiment except if requiredto illustrate a difference. It will be appreciated that apart from thefollowing discussion the second embodiment is the same as the first. Inthis embodiment dome (53) is omitted though a suitable protectivehousing could be provided.

The mounting arms (33 and 34) support the drive means (6) such that thedrive means may be rotated between three configurations illustrated inFIGS. 8, 9 and 10. The drive means may be secured in any positionbetween the two extremes depicted in FIGS. 8 and 9. It will be notedthat the scale (38) is extended to ±180° with 0° corresponding to thelaser irradiating a plain parallel to the top of the platform means.

The mounting arms are offset from the centre of the top of the platformmeans such that the laser means (9) may irradiate in a plane coincidentwith the first axis. The platform means and body means have aperturemeans, one shown as (87) and better seen in FIG. 11 such that the firstaxis is unobstructed. There are corresponding apertures in the bodymeans (2) and circuit board (32). Further, the body means is fastened tothe platform (13) and tripod by means of a bolt (88) with a coaxialcentral hole (89) therethrough screwing into threaded central hole (14).

This arrangement allows the laser to irradiate through the apparatus andstand so as to give a plumb line should the platform means be level.Further, this plumb line can be used to accurately align the apparatusover a style marking a specific reference point on a work site. Sincethe laser irradiation in the configuration shown in FIG. 9 is a planecoincident with the first axis rotation of the platform means does notchange the relative position of the spatial position of the laser head.Compare FIG. 9 with FIG. 2 and it will be appreciated that the plane ofirradiation is offset from the first axis and rotation of the platformmeans circumscribes as circle about the first axis. This featurefacilitates ease of marking out construction sites.

To minimise obstruction of the laser light shinning from the apparatusthe wires (21) from the batteries are passed through a conduit (90). Aring (91) is provided at the lower end of shaft (19). It will berecalled that the platform means can rotate with respect to the bodymeans by somewhat less than 360° in any one direction. The connectionfor the wires (21) on the circuit board and the batteries are aligned sothat substantially equal rotation in each direction of the platformmeans relative to the body means may be accommodated.

It will be appreciated that the detector or sensor (56) is independentof and movable with respect to the body means. Further, being twoorthogonal intersecting arrays of laser beam detectors adapted to detectthe laser radiation and indicate which beam detectors are beingirradiate it thereby indicates whether the sensor is above, below, leftor right of the plane or line of the laser radiation. In this fashion,particularly with the second embodiment, a line may be determined at adesired relative orientation to the laser level to another remote point.Such a line could be level with the laser level and at a desiredrelative rotation, or it can be at a tilted angle.

A third embodiment differs from the previously mentioned two embodimentsin the following manner with reference to FIGS. 12, 13 and 14. The headmeans (92) is the same as previously mentioned excepting that itincludes a slot (93) in front of the laser emission window (94). Intothis slot a prism (95) may be inserted. The prism may be manufacturedaccording to known techniques such as etching to spread the spot beam ofthe laser into other shapes such as a line illustrated in FIG. 13 or twointersecting orthogonal lines illustrated in FIG. 14. The divergencecaused by the prism is a matter of constructional choice. Whilst the useof a slot and a separate prism is illustrated here it will beappreciated that a combination prism with an unaltering portion, asingle horizontal line generating portion, a single vertical linegenerating portion and a crossed vertical and horizontal lines. Theprism can be slidable in a housing in front of the laser emission window

The third embodiment finds application in marking out of internalfitments to a building. In such applications the laser beam intensity isgreat enough to be seen and the distance between laser level and markingposition not great therefor any divergence in the laser beam need not betoo great to be unacceptable to the application. For example, in settingout the frame of a cupboard and bench top the two intersectingorthogonal lines may be used to indicate a corner of the frame.

It will be appreciated that this disclosure is not intended to limit theinvention to the preferred embodiment or details thereof. It is intendedto give an overview of the invention as conceived and other embodimentswill be apparent to the skilled addressee all of which fall within thespirit of the invention.

What is claimed is:
 1. A laser level apparatus including: body means,platform means supported by the body means and selectively pivotableabout a first axis, drive means supported in the platform means andselectively pivotable about a second axis transverse to the first axis,the drive means including an electric motor a rotor of which is coaxialwith a third axis transverse to the second axis, the rotor having twoaxial electrical conductors insulated one from the other, and a firstrotatable electrical connection means and a second rotatable electricalconnection means each electrically connected with a respective one ofthe two axial electrical conductors. head means supported on a rotatableshaft coaxial with and connected to the rotor, the head means beingadapted to be selectively rotated by the drive means about the thirdaxis, laser means supported within the head means to selectively projectlaser radiation from the head means transverse the third axis, the lasermeans includes a semiconductor laser electrically connected to the twoaxial electrical conductors and adapted to produce the laser radiation,and electrical power source and control means connected to the first andsecond rotatable electrical connectors to selectively supply electricalpower to the semiconductor laser and the electric motor.
 2. A laserlevel apparatus as in claim 1 wherein the laser radiation projected bythe laser means is perpendicular to the third axis, the third axis isperpendicular to the second axis, the second axis is perpendicular tothe first axis, and the drive means may be selectively rotated to afirst configuration where the third axis is substantially parallel orcoaxial with the first axis and to a second configuration where thethird axis is substantially perpendicular to the first axis.
 3. A laserlevel apparatus as in claim 2 wherein the body means has leveling meansto enable adjustment of the support of the platform means such that thefirst axis is within a vertical plane, and thereby when the apparatus isin the first configuration the laser radiation projected by the lasermeans is within a horizontal plane and when the apparatus is in thesecond configuration the laser radiation projected by the laser means iswithin a vertical plane.
 4. A laser level apparatus as in claim 2wherein the drive means may be selectively rotated and secured in aconfiguration between the first and second configurations.
 5. A laserlevel apparatus as in claim 1 wherein the first rotatable electricalconnection means and the second electrical connection means respectivelyincludes electrical brush arrangements.
 6. A laser level apparatus as inclaim 3 wherein the leveling means includes two spirit bubbles settransverse to each other and within or upon the platform means forindication of levelness of the platform means, and foot screws spacedabout the platform means and acting against the body means with which toadjust the relative position of the platform means with respect to thebody means and thereby with the spirit bubbles permit the leveling ofthe platform means.
 7. A laser level apparatus as in claim 3 wherein theleveling means includes two spirit bubbles set transverse to each otherand within or upon the platform means for indication of levelness of theplatform means, and the platform means includes a shaft projectingsubstantially perpendicular to a platform plate and substantiallyparallel to the first axis into the body means through a first hole andtwo spring means acting at substantially a distal end of the shaft tobias the shaft against the action of two radially spaced transverseacting screws with which the platform means may be leveled by tiltingthe shaft relative to the body means.
 8. A laser level apparatus as inclaim 3 wherein the leveling means includes semi-automated or automatedmeans to effect leveling of the platform means.
 9. A laser levelapparatus as in claim 1 including a stand for supporting the body meansin an elevated position above a floor or ground surface.
 10. A laserlevel apparatus as in claim 1 wherein either the platform means includesa graduated circular scale and the body means includes an indicator markor vice versa, therewith the rotation of the platform means about thefirst axis can be determined.
 11. A laser level apparatus as in claim 10wherein the graduated circular scale is selectively rotatable andsecurable thereby permitting the scale to be set to the indicator markand the platform means rotated a desired quantity of rotation indicatedby the scale.
 12. A laser level apparatus as in claim 11 wherein theplatform means or the body means as the case may be includes a ring uponwhich the indicator mark is, and the ring is selectively rotatable andsecurable thereby permitting the indicator mark to be rotated to a pointclosest to the graduated circular scale.
 13. A laser level apparatus asin claim 1 wherein either the platform means includes a graduated scaleand the drive means includes an inclination mark or vice versa,therewith the rotation of the drive means about the second axis can bedetermined and set thereto.
 14. A laser level apparatus as claim 1wherein the control means controls the rotational position of theelectric motor and the active state of the laser means.
 15. A laserlevel apparatus as in claim 1 wherein the control means is containedwithin the platform means and connected to the electric motor and lasermeans via electrical wiring.
 16. A laser level apparatus as in claim 1wherein the laser head includes means to collimate the laser withrespect to the third axis.
 17. A laser level apparatus as in claim 1wherein the laser head includes support means for supporting the laserwithin the laser head, the support means including a resilient firstbearing means adapted to provide a firm hold of the laser, and a secondbearing means including a resilient bearing surface spaced apart fromthe first bearing means against which an adjustable means presses thelaser to provide collimating adjustment.
 18. A laser level apparatus asin as in claim 1 wherein the apparatus is one including a remote controlunit adapted to transmit control setting signals to a receiver withinthe control means thereby to effect control of the electric motor andthe laser means.
 19. A laser level apparatus as in claim 1 wherein thedrive means is supported by the platform means such that the laser headmay be rotated so that the laser means lies within a plane within whichthe first axis lies.
 20. A laser level apparatus as in claim 19 whereinthe platform means and body means have aperture means such that thefirst axis is unobstructed and that the laser means may project laserradiation through the platform means and body means.
 21. A laser levelapparatus as in claim 1 wherein the drive means is supported by theplatform means so as to be rotatable through 180° relative to theplatform means.
 22. A laser level apparatus as in claim 1 including asensor of the laser radiation which is independent of and moveable withrespect to the body means, the detector including two orthogonalintersecting arrays of laser beam detectors adapted to detect the laserradiation and indicate which beam detectors are being irradiate andthereby the sensor indicates whether the sensor is above, below, left orright of the plane or line of the laser radiation.
 23. A laser levelapparatus as in claim 1 including a prism mountable in front of thelaser adapted to spread the laser beam into a line.
 24. A laser levelapparatus as in claim 23 wherein the prism is adapted to spread thelaser beam into two intersecting orthogonal lines.
 25. A laser levelapparatus as in claim 1 wherein the electric motor is a stepper motor.26. A laser level apparatus as in claim 1 wherein the electric motor isa D.C. chopper motor.
 27. A laser level apparatus as in either claim 25or 26 wherein the control means permits control of the electric motorsuch that it may be rotated to a desired rotational position, oscillatedbetween two rotational positions, or continually rotate about the thirdaxis.